David Cameron will attempt to shed the Tories' image as the party of the rich and privileged tomorrow by pledging to divert billions of pounds to healthcare in the most deprived areas of the country.

The promise to direct a higher share of NHS resources to boost health in run-down areas was described last night by a senior party source as proof that Gordon Brown's "class war" attacks on the Conservatives were baseless.

The move comes as the main parties fire the opening shots in what promises to be the longest, most bitterly fought and possibly closest general election campaign since 1974. The most likely day for voters to go to the polls is 6 May.

In an article for today's Observer, Brown joins the battle for the support of middle England, going out of his way to stress that "New Labour" is very much alive as the party of "aspiration" and is fizzing with ideas and optimism.

Tomorrow he and Ed Balls, the schools secretary, will make a series of announcements on education, including plans to expand the number of specialist teachers from primary schools upwards.

Balls will announce that pupils aged seven onwards will be able to learn languages including Mandarin and Arabic to meet the challenges of a globalised world. Officials cited CBI surveys showing that 52% of employers looking for language skills now want people with French, 43% with German and 38% with Mandarin/Cantonese. They said Labour was keen to prepare the next generation of workers for the new global economy.

"Our priority is to offer not a gamble, but a guarantee," Brown writes, "[with] public services that are also personal services tailored to people's needs, legally enforceable rights for personalised education, health, social care and policing, not just for some but for all."

He adds: "With our laser focus on school standards, guaranteed support for school-leavers and new plans to equip all of our people for the challenging times ahead, I know there is nothing our country can't achieve in the decade to come."

In a speech launching his election themes yesterday, Cameron called on voters to make 2010 "the year of change" and attacked Brown for his class war approach to politics. "We can't go on with an old-fashioned leftwing class war on aspiration from a government that has seen the rich get richer and the poor get poorer," he said.

The Tories, Cameron insisted, would support the NHS because it was "the embodiment of fairness in our society". "We recognise its special place in our society so we will not cut the NHS; we will improve it for everyone.

"It's because we are progressives that we will support aspiration so that people from every background, not just the rich, have the chance to get on in life."

The decision on health funding will be the first in a series of policy statements by the Tories aimed at silencing those who claim they are intent on slashing core public services.

The commitment to reshape the NHS budget by directing more to the neediest represents a dramatic shift from Conservative policy in the 2005 election, when the party went to the polls offering to subsidise those who chose to have their treatment in private hospitals.

Liberal Democrat frontbencher Danny Alexander said Cameron "needs to be honest with people about his real priorities rather than simply parroting lines from spin doctors". The Tory leader would be judged on his actions and the electorate "will see that he only offers phoney change, not the real thing".

Brown argues today that the Tories cannot be trusted with the public services. "Ask yourself why, in contrast to the Conservatives, only New Labour is ready to guarantee cancer diagnosis within a week to everybody and not just those who can pay? Why it is only New Labour that is sticking up for the law-abiding majority by guaranteeing to fund high-quality neighbourhood policing in every ward, matched by zero tolerance of knife, gun and drug crime?"

Balls said yesterday: "In this new decade, our ties with emerging economies like China will become even more important and it's vital that young people are equipped with the skills they need. That's why we want all secondary pupils to have the opportunity to learn Mandarin if they choose, either at their own school or a nearby school or college."

■ Ken Clarke last night said a Conservative government would be ready to increase taxes to reduce the UK's deficit. When asked about VAT, which some observers expect the Tories to raise to 20% if they win power, the shadow business secretary told the Sunday Telegraph: "When you're the most indebted country in the western world... you cannot start promising you are not ever going to start increasing taxation."